Isolation, selection, and identification of phytopathogenic fungi with bioherbicide potential for the control of field bindweed (Convolvulus arvensis L.)

Abstract

Field bindweed (Convolvulus arvensis L.) has been described as one of the most noxious weeds in agricultural soils worldwide. Furthermore, its control by conventional herbicides can promote the emergence of resistant biotypes as well as negatively affect human health and the environment. An ecological alternative for weed management is the use of phytopathogenic fungi. In this study, 68 fungal strains were isolated from C. arvensis leaves exhibiting symptoms of fungal disease. Seven isolates were confirmed as pathogenic to C. arvensis in a detached leaf assay. Filtered cell-free cultures (FCFC) of these seven isolates were then evaluated. FCFC of TV1 and ET4 showed the best results, inhibiting seedling dry weight by up to 48% in vivo and shoot dry weight up to 35% in growth chamber assays. Phytopathogenic evaluation of both isolates showed disease severity >67%, and an ability to inhibit root dry weight by up to 80%. Inhibitory effects were not observed on chickpea, bean, sorghum, maize, or tomato plants, suggesting pathogenic specificity of TV1 and ET4 to field bindweed. Molecular identification revealed a high similarity of TV1 (100% identity) with Macrophomina phaseolina, and a high similarity of ET4 with Alternaria alternata (99.8% identity). To the best of our knowledge, this is the first report of M. phaseolina showing pathogenicity against field bindweed worldwide, and the first report for A. alternata in Mexico. The results reveal that these fungi and/or their FCFC have the potential to be used as bioherbicidal agents against C. arvensis.